USPS Postal Address API

 USPS has developed a web interface to validate addresses for free. There are several service providers offering limited address lookups, but none is completely free. With this interface, you can enter a valid address and receive feedback if it is invalid. Nevertheless, you cannot validate addresses in bulk, as USPS does not provide the ZIP+4 delivery point or a two-digit delivery point. Consequently, this service is only suitable for a limited range of purposes.

The USPS postal address API is available for free, but you have to register an account in order to use it. Additionally, you can only use it for mailing and shipping services. You cannot use it for database cleansing or record management. You can only use it in conjunction with USPS mailing services, and only on an individual transactional basis. Therefore, it is a good idea to check for any limitations before implementing it.

The USPS postal address API does not include any data that would make the database a more comprehensive one. It also does not support the merging of multiple addresses at a time. While the USPS postal address API is not suited for such tasks, it does offer examples of use and is not difficult to implement. If you are a developer, you can use the Python, JavaScript, C#, or iOS version of the API to develop a web application that uses addresses.

Besides USPS postal address API, you can also use ZipCode download to access USPS data in bulk. Its ZIP+4 code lookup service will provide the city and state of an address. Its purpose is to improve the efficiency of delivery. In addition, the USPS also has an Address Validation / Standardization API that can validate addresses. This service is free, but it may not be the best option for you.